With the antikink hydraulic system as the research object, the composite damping principle of the system is analyzed for lateral damping function and a mathematical model for damping properties is established. A hydraulic simulation model was established by the application of AMESim to compute the damping properties. At the same time, the influence of the design parameters of the buffer valve group on the damping characteristics of the system was studied. The research shows that the combination of throttle valve and relief valve in the buffer valve group forms the damping characteristic of the antikink hydraulic system with several break points in multi-segment parabola. The opening pressure of relief valve determines the peak damping force, and the orifice size of the throttle valve determines the minimum critical velocity of the steering piston corresponding to the peak damping force. The research provides a reference for the design and optimization of the antikink hydraulic system.